The invention relates to the processing of air in and around the machines which are used for the making of smokers' products incuding machines for the making of plain cigarillos, cigarettes, cigars or other rod-shaped articles which contain natural, synthetic and/or reconstituted tobacco, machines for the making of filter cigarettes, cigars, cigarillos and analogous articles of the tobacco processing industry, as well as the machines for the making of filter rods and filter rod sections for tobacco smoke.
Many types of machines for the making of smokers' products utilize large quantities of air for a variety of different purposes. For example, a machine for the making of plain cigarettes or a filter tipping machine (wherein plain cigarettes or other rod-shaped articles containing natural, reconstituted and/or synthetic tobacco are united with filter rod sections of unit length or multiple unit length to form filter cigarettes, cigars or the like) can utilize air for the transport of tobacco or filter material, for classification of randomly intermixed lighter and heavier and/or shorter or longer particles (such as mixtures of shreds of tobacco leaf laminae and fragments of tobacco eyes or ribs), for attracting webs of paper or the like or streams of tobacco and/or filter material to their conveyors, for attracting rod-shaped tobacco- and/or filter sections to the flutes of rotary conveyors or to other types of conveyors during transport and/or other manipulation, for testing rod-shaped articles and/or their constituents and/or for ejecting defective rod-shaped articles and/or their components. Air which is used for such purposes is normally laden with (i.e., it contains at least some) solid impurities including larger and/or smaller fragments of tobacco, larger and/or smaller fragments of filter material and/or other foreign bodies (such as pieces of rock, sand, metal or the like). Such contaminated air must be processed prior to reintroduction into a machine for the making of smokers' products and/or prior to admission into the surrounding atmosphere. Furthermore, it is often desirable to recover certain solid contaminants, such as certain sizes and/or types of tobacco particles, for reintroduction into the machine or machines for the making of rod-shaped and/or other smokers' products.
Certain heretofore known proposals to regenerate or recondition air which has been used in a machine for the making of smokers' products are described, for example, in British patent No. 953,792.